Intermediate for biotin and process for producing the same

ABSTRACT

The present invention is to provide a process for preparing a synthetic intermediate of biotin which is industrially advantageous, and discloses a process for preparing a compound represented by the formula (I): 
     
       
         
         
             
             
         
       
         
         
           
             wherein R 1  and R 2  may be the same or different from each other, and each represents hydrogen atom, a benzyl group which may have a substituent(s) on the benzene ring, a benzhydryl group which may have a substituent(s) on the benzen ring, or a trityl group which may have a substituent(s) on the benzene ring, R 3  represents cyano group, carboxyl group, an alkoxycarbonyl group, an alkylthiocarbonyl group, or a carbamoyl group which may have a substituent,
 
or a salt thereof which comprises subjecting a compound represented by the formula (II-a):
 
           
         
       
    
     
       
         
         
             
             
         
       
         
         
           
             wherein the symbols have the same meanings as defined above,
 
or a salt thereof to ring transformation.

TECHNICAL FIELD

The present invention relates to a biotin synthetic intermediate and aprocess for preparing the same, and a process for preparing biotin usingsaid intermediate.

BACKGROUND ART

Biotin is a vitamine useful as an additive for feed, medicine, etc., andas a process for preparing the same, it has been known a process, forexample, in which a thienoimidazol compound represented by the followingformula:

is used as a synthetic intermediate (Chemical Reviews, vol. 97, No. 6,pp. 1755-1792, 1997, Japanese Patent Publications No. Sho. 49-32551 andSho. 53-27279, Japanese Patent Publications No. Hei. 3-66312 and Hei.5-9064) and the like.

However, these conventionally known processes involve the problems thatits preparation steps are long, and they require complicated opticalresolution in the course of the preparation steps.

An object of the present invention is to provide a process for preparingbiotin which is industrially advantageous.

DISCLOSURE OF THE INVENTION

To solve the problems, the present inventors have earnestly studied, andas a result, they have found that a process for preparing biotin throughCompound (I) and Compound (III) or di(imidazolydinylmethyl)disulficecompound (IV) as a synthetic intermediate can give the above-mentionedthienoimidazole compound inexpensively, so that this is an industriallyexcellent preparation process, whereby they have accomplished thepresent invention.

That is, the present invention relates to a process for preparing acompound represented by the formula (I):

-   -   wherein R¹ and R² may be the same or different from each other,        and each represents hydrogen atom, a benzyl group which may have        a substituent(s) on the benzene ring, a benzhydryl group which        may have a substituent(s) on the benzen ring, or a trityl group        which may have a substituent(s) on the benzene ring, R³        represents cyano group, carboxyl group, an alkoxycarbonyl group,        an alkylthiocarbonyl group, or a carbamoyl group which may have        a substituent,        or a salt thereof, which comprises subjecting a compound        represented by the formula (II-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof to ring transformation.

Also, the present invention relates to a process for preparing acompound represented by the formula (III):

-   -   wherein the symbols have the same meanings as defined above,        which comprises preparing a compound represented by the formula        (I):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof according to the above-mentioned process,        subjecting to hydrolysis, depending on necessity to prepare a        compound represented by the formula (I-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof, and then, subjecting the obtained Compound        (I-a) to cyclization and epimerization.

The present invention also relates to a process for preparing a compoundrepresented by the formula (IV):

-   -   wherein the symbols have the same meanings as defined above,        which comprises subjecting a compound represented by the formula        (II):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof to ring transformation and cyclization.

The present invention also relates to a process for preparing a compoundrepresented by the formula (III):

-   -   wherein the symbols have the same meanings as defined above,        which comprises reducing a compound represented by the formula        (IV-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof according to the above-mentioned method,        subjecting to hydrolysis depending on necessity, to prepare a        compound represented by the formula (I-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof, and then, subjecting the resulting Compound        (I-a) to cyclization and epimerization.

Also, the present invention relates to a process for preparing acompound represented by the formula (III):

-   -   wherein the symbols have the same meanings as defined above,        which comprises subjecting a compound represented by the formula        (II-b):

-   -   wherein R³¹ represents carboxyl group, an alkoxycarbonyl group,        an alkylthiocarbonyl group, or a carbamoyl group which may have        a substituent(s), and other symbols have the same meanings as        defined above,        or a salt thereof to ring transformation and cyclization.

The present invention also relates to a process for preparing a compoundrepresented by the formula (6-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof, which comprises reacting a compound        represented by the formula (5-a):

-   -   wherein the symbol has the same meaning as defined above,        or a salt thereof with a compound represented by the formula        (7):        R²—NH₂  (7)    -   wherein the symbol has the same meaning as defined above,        and a cyanide compound.

The present invention further relates to a process for preparing acompound represented by a compound represented by the formula (6-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof, which comprises oxidizing a compound        represented by the formula (4-a):

-   -   wherein the symbol has the same meaning as defined above,        or a salt thereof to prepare a compound represented by the        formula (5-a)

-   -   wherein the symbol has the same meaning as defined above,        or a salt thereof, and then, reacting the resulting Compound        (5-a) with a compound represented by the formula (7):        R²—NH₂  (7)    -   wherein the symbol has the same meaning as defined above,        and a cyanide compound.

The present invention further relates to a process for preparing acompound represented by a compound represented by the formula (III):

-   -   wherein the symbols have the same meanings as defined above,        which comprises preparing a compound represented by the formula        (6-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof according to the above-mentioned method,        subjecting the resulting Compound (6-a) to hydrolysis to prepare        a compound represented by the formula (II-c):

-   -   wherein the symbols have the same meanings as defined above,        then, subjecting the resulting Compound (II-c) to ring        transformation to prepare a compound represented by the formula        (I-b):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof, subjecting the resulting Compound (I-b) to        hydrolysis to prepare a compound represented by the formula        (I-a):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof, and subjecting the resulting compound (I-a)        to cyclization and epimerization.

Further, the present invention relates to a process for preparing acompound represented by a compound represented by the formula (VII):

which comprises preparing a compound represented by the formula (III):

-   -   wherein the symbols have the same meanings as defined above,        according to the above-mentioned method, reacting the resulting        Compound (III) with a compound represented by the formula (V):        X¹Zn—(CH₂)₄R⁴  (V)    -   wherein X¹ represents a halogen atom, and R⁴ represents an        esterified carboxyl group or an amidated carboxyl group,        to give a compound represented by the formula (VI):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof, then, reducing the resulting Compound (VI),        and subjecting it to hydrolysis, if necessary, and further        converting R¹ and/or R² to hydrogen atom, if necessary.

Moreover, the present invention relates to adi(imidazolidinylmethyl)disulfide compound represented by the formula(IV):

-   -   wherein the symbols have the same meanings as defined above,        or a salt thereof.

Moreover, the present invention relates to a process for preparing acompound represented by a compound represented by the formula (IX):R—X—Y  (IX)

-   -   wherein X represents zinc or magnesium, and Y represents iodine,        bromine or chlorine,        which comprises reacting a compound represented by the formula        (VIII):        R—I  (VIII)    -   wherein R represents an alkyl group which may have a        substituent(s), a bicyclo group which may have a substituent(s),        an alkenyl group which may have a substituent(s), a heterocyclic        group which contains 1 to 4 atoms selected from nitrogen atom,        oxygen atom and sulfur atom as a hetero atom(s) (said        heterocyclic group may have a substituent(s)) or an aryl group        which may have a substituent(s),        with zinc or magnesium which has been treated by chlorine,        bromine, hydrogen chloride or hydrogen bromide.

Also, the present invention further relates to a process for preparing acompound represented by a compound represented by the formula (IX):R—X—Y  (IX)

-   -   wherein the symbols have the same meanings as defined above,        which comprises reacting a compound represented by the formula        (VIII):        R—I  (VIII)    -   wherein R has the same meaning as defined above,        with zinc or magnesium in the presence of a salt represented by        the formula (X):        M-Y  (X)    -   wherein M represents a metal atom, Y has the same meaning as        defined above.

BEST MODE FOR CARRYING OUT THE INVENTION

Compound (I) to be used or obtained in the present invention can beobtained by subjecting Compound (II-a) to ring transformation. Thisreaction can be carried out in the absence of oxygen, for example, undernitrogen or argon atmosphere, etc. This reaction can be carried out in asuitable solvent or in the absence of a solvent. As the solvent, anysolvent which does not cause any unfavorable effect to the reaction maybe used, and there may be preferably used, for example,N,N-dimethylformamide, dimethylsulfoxide, N,N-dimethylacetamide,N-methyl-2-pyrrolidone or a mixed solvent of the above-mentionedsolvents. The present reaction preferably proceeds at 0° C. to 200° C.,particularly preferably at 80° C. to 100° C.

In R¹ and R² of Compound (I), Compound (I-a), Compound (I-a′), Compound(I-b), Compound (II), Compound (II′), Compound (II-a), Compound (II-b),Compound (II-c), Compound (III), Compound (III-a), Compound (IV),Compound (IV-a), Compound (VI), Compound (6) and Compound (6-a) to beused or obtained in the present invention, and in R¹ of Compound (3),Compound (4), Compound (4-a), Compound (5) and Compound (5-a) to be usedor obtained in the present invention, and in R² of Compound (7), as asubstituent(s) on the benzene ring of the benzyl group, a group selectedfrom a halogen atom, an alkyl group and an alkoxy group may bementioned, and as a substituent(s) on the benzene ring of the benzhydrylgroup, the same or different group(s) selected from a halogen atom, analkyl group and an alkoxy group may be mentioned, and as asubstituent(s) on the benzene ring of the trityl group, the same ordifferent group(s) selected from a halogen atom, an alkyl group and analkoxy group may be mentioned.

On the respective benzene rings of the above-mentioned benzyl group,benzhydryl group or trityl group, the same or different 1 to 3above-mentioned substituent(s) may be substituted.

In R³ of Compound (I), Compound (II), Compound (II-a), Compound (IV) andCompound (IV-a) to be used or obtained in the present invention and inR³¹ of Compound (II-b), as a substituent(s) for a carbamoyl group, thesame or different 1 or 2 alkyl group(s) may be mentioned.

As Compound (I), Compound (I-a), Compound (I-a′), Compound (I-b),Compound (II), Compound (II′), Compound (II-a), Compound (II-b),Compound (II-c), Compound (III), Compound (III-a), Compound (IV),Compound (IV-a), Compound (VI), Compound (6) and Compound (6-a) to beused or obtained in the present invention, a compound in which R¹ and R²are both benzyl groups, benzhydryl groups or trityl groups is preferred.Of these, particularly preferred is a compound in which R¹ and R² areboth benzyl groups. Also, as Compound (I), Compound (II), Compound(II-a), Compound (IV) and Compound (IV-a), a compound in which R³ iscarboxyl group, an alkoxycarbonyl group or a carbamoyl group ispreferred.

Compound (IV) to be used or obtained in the present invention can beprepared by subjecting Compound (II) to ring transformation in thepresence of a base.

As a base, there may be preferably used an alkali metal carbonate(sodium carbonate, potassium carbonate, etc.), an alkali metal hydrogencarbonate (sodium hydrogen carbonate, etc.), an organic acid alkalimetal salt (sodium acetate, etc.), an alkali metal hydroxide (sodiumhydroxide, potassium hydroxide, etc.), an alkali metal hydride (sodiumhydride, etc.), an alkali metal amide (sodium amide, lithium amide,etc.), an alkali metal alkoxide (sodium methoxide, etc.), an alkalimetal phosphate, an alkali metal (sodium, etc.) or an organic base(triethylamine, diisopropylethylamine, morpholine, N-methylmorpholine,pyridine, piperidine, dimethylaniline, dimethylaminopyridine, etc.) andthe like. Of these, sodium hydrogen carbonate or sodium acetate isparticularly preferred.

An amount of the base to be used is preferably 0.1 molar equivalent to100 molar equivalent, particularly 1 molar equivalent to 3 molarequivalent based on the amount of Compound (II).

This reaction can be carried out in a suitable solvent or in the absenceof a solvent. As the solvent, any solvent which does not cause anyunfavorable effect to the reaction may be used, and there may bepreferably used, for example, N,N-dimethylformamide, dimethylsulfoxide,N,N-dimethylacetamide, N-methylpyrrolidine or a mixed solvent of theabove-mentioned solvents. The present reaction preferably proceeds at 0to 200° C., particularly preferably at 80 to 100° C.

In Compound (IV) to be used in the present invention, optical isomersbased on an asymmetric carbon exist, and it may be either a racemicmixture or an optical isomer. Of these, an optically active (+)-biotinalone has biological activity, so that an optical isomer in which5-position (the position to which —CH₂S— binds) of the imidazolidinering is an R configuration is preferred to lead it to (+)-biotin withgood efficiency.

As Compound (VI) to be used or obtained in the present invention, acompound in which R¹ and R² are both benzyl groups, benzhydryl groups ortrityl groups, and R⁴ is an alkoxycarbonyl group or an alkylcarbamoylgroup is preferred. Of these, particularly preferred is a compound inwhich R¹ and R² are both benzyl groups, benzhydryl groups or tritylgroups, and R⁴ is an alkoxycarbonyl group.

Compound (II) and Compound (II-a) can be prepared by conventionallyknown methods described in Bulletin of Chemical Society of Japan, vol.37., No. 2, pp. 242-244, 1964, Analytical Biochemistry, vol. 138, pp.449-450, 1984, Heterocycles, vol. 18, pp. 259-263, 1982, etc. or methodsin accordance with the above methods, and, for example, these compoundscan be prepared as follows.

-   -   wherein X² represents a halogen atom, R³² represents carboxyl        group or a carbamoyl group, and other symbols have the same        meanings as defined above.

The step of producing Compound (2) from Compound (1) and phenylchloroformate (or alkyl chloroformate) can be carried out in thepresence of a base in a solvent or in the absence of a solvent. As thebase, there may be preferably used an alkali metal hydroxide, an alkalimetal carbonate, an alkali metal hydrogen carbonate, an alkali metalalkoxide, an organic base, etc. As the solvent, any solvent which doesnot cause any unfavorable effect to the reaction may be used, and theremay be mentioned, for example, toluene, benzene, xylene tetrahydrofuran,1,4-dioxane, diethyl ether, dichloromethane, water, etc. The presentreaction preferably proceeds at −30° C. to 120° C., particularlypreferably at 20° C. to 50° C.

In Compound (3), a compound in which R¹ has a substituent other thanhydrogen atom can be prepared by reacting Compound (2) and R¹—X²(chloride, bromide, etc. of R¹) in the presence of a base and a highpolar solvent such as dimethylsulfoxide, etc., in a solvent or in theabsence of a solvent. As the base, there may be preferably used analkali metal hydroxide, an alkali metal carbonate, an alkali metalhydrogen carbonate, an alkali metal alkoxide, an organic base, etc. Asthe solvent, any solvent which does not cause any unfavorable effect tothe reaction may be used, and there may be mentioned, for example,water, N,N-dimethylformamide, N,N-dimethylacetamide,N-methyl-2-pyrrolidone, methanol, etc. The present reaction preferablyproceeds at −20° C. to 120° C., particularly preferably at 15° C. to 40°C.

Compound (4) can be produced by reacting Compound (3) with a reducingagent, in the presence of an acid or an alkylating agent, in a solventor in the absence of a solvent. As the reducing agent, there may bepreferably used sodium borohydride, lithium borohydride, lithiumaluminum hydride, Red-Al (bis(2-methoxyethoxy)aluminum sodium hydride),diborane, borane methylsulfide complex, etc. As the acid, there may bepreferably used sulfuric acid, hydrogen chloride, a Lewis acid(trimethylsilyl chloride, iodine, chlorine, borane trifluoride ethercomplex, etc.), etc. As the alkylating agent, there may be preferablyused dimethyl sulfate, methyl iodide, benzyl halide, etc. As thesolvent, any solvent which does not cause any unfavorable effect to thereaction may be used, and there may be mentioned, for example,tetrahydrofuran, ethanol, etc. The present reaction preferably proceedsat −30° C. to 120° C., particularly preferably at 0° C. to 40° C.

Compound (5) can be produced by reacting Compound (4) in the presence ofan oxidizing agent, in a solvent or in the absence of a solvent. As theoxidizing agent, there may be preferably used (1) that comprisingdimethylsulfoxide, sulfur trioxide pyridine complex salt and an amine(diisopropylethylamine, triethylamine, etc.), (2) that comprisingdimethylsulfoxide, oxalyl chloride and an amine (diisopropylethylamine,triethylamine, etc.), (3) that comprising dimethylsulfide, chlorine andan amine (diisopropylethylamine, triethylamine, etc.), (4) thatcomprising sodium hypochlorite, sodium hydrogen carbonate, sodiumbromide, and 4-hydroxytetramethylpiperidineoxide or its derivative(4-aminotetramethylpiperidineoxide, 4-carboxytetramethylpiperidineoxide,4-cyanotetramethylpiperidineoxide, etc.), (5) chromic acid and its salt,(6) a metal catalyst (platinum, palladium, etc.) and oxygen, (7) aperacid and a peroxide, or (8) dimethylsulfoxide, DCC(dicyclohexylcarbodiimide), a base (pyridine, etc.), an acid(trifluoroacetic acid, phosphoric acid, etc.) (Pfitzner-Moffattoxidation) and the like. As the solvent, any solvent which does notcause any unfavorable effect to the reaction may be used, and there maybe mentioned, for example, dimethylsulfoxide, dichloromethane, water,benzene, toluene, etc. The present reaction preferably proceeds at −78°C. to 100° C., particularly preferably at −78° C. to 25C.

Also, Compound (5) can be also prepared by halogenating the carboxylgroup of Compound (3) with thionyl chloride, oxalyl chloride, etc., thensubjecting to catalytic reduction by using a metal catalyst (platinum,palladium, etc.) and hydrogen, without through Compound (4).

Compound (6) can be prepared by carrying out a step of reacting Compound(5) with R²—NH₂ and step of reacting with a cyanide compound in asolvent or in the absence of a solvent. The reaction of Compound (5) andR²—NH₂ can be preferably carried out by reacting them with a cyanidecompound in the presence of a dehydrating agent (Molecular Sieves 4A,magnesium sulfate, sodium sulfate, etc.). The cyanide compound is acompound which is usually used when cyanation is carried out, and theremay be mentioned, for example, hydrocyanic acid, alkali metal cyanide ororganic cyanide, etc., and of these, an alkali metal cyanide ispreferably used. As the alkali metal cyanide compound, there may bementioned, for example, lithium cyanide, sodium cyanide, potassiumcyanide, etc., and as the organic cyanide, there may be mentioned, forexample, trimethylsilyl cyanide, tributyl tin cyanide, dimethylaluminumcyanide, tetraethyl ammonium cyanide, etc.

As the solvent, any solvent which does not cause any unfavorable effectto the reaction may be used, and there may be mentioned, for example,dichloromethane, toluene, acetonitrile, acetone, ethyl acetate, diethylether, tetrahydrofuran, 1,4-dioxane, etc. The reaction of Compound (5)and R²—NH₂ preferably proceeds at −50° C. to 100° C., particularlypreferably at 0° C. to 20° C. Also, the step of reacting with a cyanidecompound preferably proceeds at −78° C. to 100° C., particularlypreferably at −20° C. to 20° C.

Compound (II′) can be prepared by using Compound (6) as follows.

Compound (II) wherein R³ is carboxyl group and Compound (II-a) whereinR³¹ is carboxyl group can be prepared by reacting Compound (6) in thepresence of an acid or a base in a solvent or in the absence of asolvent. As the acid, sulfuric acid, hydrochloric acid, etc. may bepreferably used. As the base, an alkali metal hydroxide, an alkali metalalkoxide, etc. may be preferably used. As the solvent, any solvent whichdoes not cause any unfavorable effect to the reaction may be used, andthere may be mentioned, for example, dichloromethane, water,tetrahydrofuran, ethanol, etc. The present reaction preferably proceedsat −30° C. to 200° C., particularly preferably at 0° C. to 100° C.

Compound (II) wherein R³ is a carbamoyl group and Compound (II-a)wherein R³¹ is a carbamoyl group can be prepared by reacting Compound(6) in the presence of an acid in a solvent or in the absence of asolvent, and further neutralizing with a base. As the acid, hydrogenperoxide, hydrochloric acid, sulfuric acid, phosphoric acid,methanesulfonic acid, etc. may be preferably used. As the base, ammonia,monomethylamine, dimethylamine, sodium hydroxide, sodium hydrogencarbonate, sodium carbonate, potassium hydroxide, potassium hydrogencarbonate, potassium carbonate, potassium phosphate, dipotassiumhydrogen phosphate, etc. may be preferably used. As the solvent, anysolvent which does not cause any unfavorable effect to the reaction maybe used, and there may be mentioned, for example, toluene,dichloromethane, tetrahydrofuran, N,N-dimethylformamide,dimethylsulfoxide, 1,4-dioxane, methyl ethyl ketone, acetone,chloroform, 1,2-dichloroethane, xylene, mesitylene, tert-butyl methylether, etc. The present reaction preferably proceeds at 0° C. to 100°C., particularly preferably at 30° C. to 50° C.

In the above-mentioned reaction, a combination of aqueous hydrogenperoxide as an acid, potassium carbonate as a base and dimethylsulfoxideas a solvent is preferred.

With regard to Compound (1), Compound (2), Compound (3), Compound (4),Compound (5), Compound (6) and Compound (II′) to be used in the presentinvention, optical isomers based on an asymmetric carbon exist, and itmay be either a racemic mixture or an optical isomer. Of these, anoptically active (+)-biotin alone has biological activity, so that tolead the compound to (+)-biotin with good efficiency by the process ofthe present invention, the following respective optical isomers arepreferred. Also, a compound wherein R³¹ of Compound (II′-a) is carboxylgroup is Compound (II-c).

-   -   wherein the symbols have the same meanings as defined above.

Also, Compound (4) can be prepared by the conventionally known processas disclosed in Heterocycles, vol. 18, pp. 259-263, 1982, etc. or amethod in accordance with the above process, and for example, it may bealso prepared as follows.

-   -   wherein the symbols have the same meanings as defined above.

Compound (11) can be prepared by reacting cysteine and triphosgene (orphosgene, phenyl chloroformate, alkyl chloroformate, etc.) in thepresence of a base (an alkali metal hydroxide, an alkali metalcarbonate, an alkali metal hydrogen carbonate, etc.) in a solvent or inthe absence of a solvent, and further reacting in the presence ofethanol and an activating agent (thionyl chloride, sulfuric acid,hydrogen chloride, oxalyl chloride, etc.). As the solvent, any solventwhich does not cause any unfavorable effect to the reaction may be used,and there may be mentioned, for example, water, 1,4-dioxane,tetrahydrofuran, diethyl ether, etc. The present reaction preferablyproceeds at −20° C. to 100° C., particularly preferably at 0° C. to 40°C.

In Compound (12), a compound in which R¹ has a substituent other thanthe hydrogen atom can be prepared by reacting Compound (11) and R¹—X²(chloride, bromide, etc. of R¹) in the presence of a base in a solventor in the absence of a solvent. As the base, an alkali metal carbonate,an alkali metal hydride, an alkali metal amide, etc. As the solvent, anysolvent which does not cause any unfavorable effect to the reaction maybe used, and there may be mentioned, for example, N,N-dimethylacetamide,acetone, acetonitrile, tetrahydrofuran, etc. The present reactionpreferably proceeds at −20° C. to 100° C., particularly preferably at15° C. to 35° C.

Compound (4) can be prepared by reacting Compound (12) in the presenceof a reducing agent in a solvent or in the absence of a solvent. As thereducing agent, sodium borohydride, lithium borohydride, lithiumaluminum hydride, Red-Al, DIBAL (diisobutylaluminum hydride), calciumborohydride, zinc borohydride, etc. can be preferably used. As thesolvent, any solvent which does not cause any unfavorable effect to thereaction may be used, and there may be mentioned, for example, ethanol,methanol, water, diethyl ether, tetrahydrofuran, 1,4-dioxane, etc. Thepresent reaction preferably proceeds at −78° C. to 50° C., particularlypreferably at −20° C. to 20° C.

Also, Compound (5) can be prepared by the conventionally known method asdisclosed in J. Am. Chem. Soc., vol. 112, pp. 7050-7051, 1990, etc. or amethod in accordance with these processes, and for example, it may beprepared as follows.

-   -   wherein the symbol has the same meanings as defined above.

Compound (13) can be prepared by reacting Compound (3) and ethanethiolin the presence of an activating agent in a solvent or in the absence ofa solvent. As the activating agent, DCC, EDC.HCl(1-[3-(dimethylamino)-propyl]-3-ethylcarbodiimide hydrochloride),chlorocarbonates, isocyanuric chloride, CDI (carbonyldiimidazole), etc.may be preferably used. In this reaction, it is more preferred tofurther add DMAP (1,4-dimethylaminopyridine) since the reaction proceedsrapidly. As the solvent, any solvent which does not cause anyunfavorable effect to the reaction may be used, and there may bementioned, for example, acetonitrile, acetone, tetrahydrofuran, benzene,toluene, etc. The present reaction preferably proceeds at −50° C. to100° C., particularly preferably at 0° C. to 20° C.

Compound (5) can be prepared by reacting Compound (13) in the presenceof a reducing agent and a catalyst in a solvent or in the absence of asolvent. As the reducing agent, silanes such as triethylsilane,trichlorosilane, triphenylsilane, etc. may be preferably used. As thecatalyst, palladium catalysts such as palladium hydroxide, palladiumcarbon, palladium black, etc. may be preferably used. As the solvent,any solvent which does not cause any unfavorable effect to the reactionmay be used, and there may be mentioned, for example, dichloromethane,acetone, tetrahydrofuran, etc. The present reaction preferably proceedsat −20° C. to 100° C., particularly preferably at 0° C. to 20° C.

Also, biotin which is the final objective product can be prepared byconverting Compound (I) or Compound (II-a) into Compound (III), then, bythe conventionally known methods as disclosed in Japanese UnexaminedPatent Publications No. Hei. 8-231553 and No. 2000-191665, and ChemicalReviews, vol. 97, No. 6, pp. 1755-1792, 1997, etc. or the method inaccordance with these methods, and for example, it may be also preparedas follows.

-   -   wherein X¹ represents a halogen atom, R⁴ represents an        esterified carboxyl group or an amidated carboxyl group, and the        other symbols have the same meanings as defined above.

Moreover, in Compound (I), when R³ is cyano group, an alkoxycarbonylgroup, an alkylthiocarbonyl group or a carbamoyl group which may have asubstituent(s), a conversion of R³ into carboxyl group (Compound (I-a))can be carried out by the conventional manner as disclosed in, forexample, “Basis and Experiment of Peptide Synthesis” written by NobuoIzumiya et al. (Maruzen Co., Ltd., 1985), or “PROTECTIVE GROUPS INORGANIC SYNTHESIS”, The Second Edition, written by Greene, et. al.,(John Wiley & Sons Co., 1991) or methods in accordance with thesemethods by hydrolysis. More specifically, for example, it can beconverted into carboxyl group by hydrolysis using a base such as analkali metal hydroxide, an alkali metal alkoxide, etc., an acid such asa mineral acid (hydrochloric acid, sulfuric acid, etc.), etc. As thesolvent, any solvent which does not cause any unfavorable effect to thereaction may be used, and there may be mentioned, for example, aceticacid, water, ethanol, tetrahydrofuran, dichloromethane, etc. The presenthydrolysis reaction preferably proceeds at 0° C. to 200° C.,particularly preferably at 50° C. to 80° C.

Compound (III) can be prepared by subjecting Compound (II-b) to ringtransformation and cyclization under a atmosphere, for example, nitrogenor argon, etc. in the absence of oxygen in a solvent or in the absenceof a solvent, or subjecting Compound (I-a) or Compound (IV-a) tocyclization and epimerization in a solvent or in the absence of asolvent.

As the solvent to be used in the step of ring transformation andcyclization of Compound (II-b), any solvent which does not cause anyunfavorable effect to the reaction may be used, and there may bementioned, for example, N,N-dimethylformamide, dimethylsulfoxide,N,N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. The present reactionpreferably proceeds at 0° C. to 200° C., particularly preferably at 80°C. to 100° C.

The cyclization and epimerization of Compound (I-a) or Compound (IV-a)in the present invention may contain both of the steps of a step inwhich cyclization is carried out and then epimerization is carried out(a step through Compound (III-a)) and a step in which epimerization iscarried out and then cyclization is carried out (a step through Compound(I-a′)).

The cyclization step of Compound (I-a) or Compound (IV-a) may bepreferably carried out in the presence of an activating agent. As theactivating agent, DCC, EDC.HCl, cyanuric chloride, etc. may bepreferably used. Also, the cyclization step can be carried out,depending on necessity, in the presence of a base to be used in theepimerization step mentioned below. The epimerization step can bepreferably carried out in the presence of a base, or without addition ofany additive under heating alone. As the base, an organic base such aspyridine, DBU (1,8-diazabicyclo[5.4.0]undeca-7-ene), triethylamine, etc.may be preferably used. Also, the epimerization step may be carried out,depending on necessity, in the presence of an acid (p-toluenesulfonicacid, hydrogen chloride, etc.).

As the solvent to be used in the cyclization and epimerization step, anysolvent which does not cause any unfavorable effect to the reaction maybe used, and there may be mentioned, for example, pyridine, toluene,tetrahydrofuran, acetone, acetonitrile, ethanol, etc. The presentreaction preferably proceeds at −20° C. to 120° C., particularlypreferably at 0° C. to 70° C.

Compound (VI) can be prepared by reacting Compound (III) and Compound(V) in the presence of a catalyst in a solvent or in the absence of asolvent, and then, subjecting to hydrolysis. As the catalyst, palladiumhydroxide, palladium carbon, palladium oxide, palladium black, tetrakistriphenylphosphine palladium, dichlorobistriphenylphosphine palladium,etc. may be preferably used. The hydrolysis reaction can be preferablycarried out in the presence of water or an acid (p-toluenesulfonic acid,hydrochloric acid, sulfuric acid, etc.). As the solvent, any solventwhich does not cause any unfavorable effect to the reaction may be used,and there may be mentioned, for example, tetrahydrofuran,N,N-dimethylformamide, toluene, etc. The present reaction preferablyproceeds at −20° C. to 200° C., particularly preferably at 30° C. to 50°C.

Biotin (VII) can be prepared by reducing Compound (VI) in a solvent orin the absence of a solvent, then subjecting to hydrolysis, and when R¹and/or R² of Compound (VI) is a group other than the hydrogen atom, byfurther converting (deprotection reaction of the protective group) ofsaid R¹ and/or R² into hydrogen atom.

The reduction can be preferably carried out, for example, by addinghydrogen in the presence of a catalyst such as palladium hydroxide,palladium carbon, palladium black, palladium chloride, palladiumacetate, palladium oxide, etc. The hydrolysis reaction can be preferablycarried out, for example, by using a base such as sodium hydroxide, etc.As the solvent, any solvent which does not cause any unfavorable effectto the reaction may be used, and there may be mentioned, for example,methanol, ethanol, tetrahydrofuran, water or a mixed solvent of theabove-mentioned solvents, etc. The present reaction preferably proceedsat 0° C. to 200° C., particularly preferably at 50° C. to 80° C.

Moreover, when R¹ and/or R² of Compound (VI) is a group other than thehydrogen atom, a step (deprotection reaction of the protective group) ofconverting said R¹ and/or R² into hydrogen atom can be carried outaccording to the conventional manner, for example, by the methoddisclosed in written by Greene, et. al., “PROTECTIVE GROUPS IN ORGANICSYNTHESIS”, The Second Edition (John Wiley & Sons Co., 1991) or a methodin accordance with the above method. As a specific example, it can bepreferably carried out by treating with a hydrohalogenic acid such ashydrobromic acid, etc., or by treating with mesitylene and an acid(methanesulfonic acid, sulfuric acid, acetic acid, etc.). As thesolvent, any solvent which does not cause any unfavorable effect to thereaction may be used, and there may be mentioned, for example, water,benzene, toluene, dichloromethane, etc. The present reaction preferablyproceeds at 0° C. to 200° C., particularly preferably at 80° C. to 100°C.

A process for producing Compound (IX) is described in HANDBOOK OFGRIGNARD REAGENTS, pp. 53-77, 1996, ORGANOZINC REAGENTS in ORGANICSYNTHESIS, pp. 18-67, 1996, etc.

In the present invention, Compound (IX) can be produced more effectivelyas compared to the methods disclosed in these literatures.

Compound (IX) can be prepared by suspending zinc or magnesium in asolvent, and after adding chlorine, bromine, hydrogen chloride orhydrogen bromide thereto, reacting with Compound (VIII). As the solvent,any solvent which does not cause any unfavorable effect to the reactionmay be used, and there may be mentioned, for example, tetrahydrofuran,toluene, diethyl ether, 1,2-dimethoxyethane, acetonitrile, 1,4-dioxane,etc., a mixed solvent of the above-mentioned solvents may be used. Thepresent reaction preferably proceeds at −50° C. to 150° C., particularlypreferably at 5° C. to 80° C.

As the substituent for the alkyl group of R, there may be mentioned analkoxycarbonyl group, an alkoxy group, an alkoxycarbonylalkenyl group,an alkoxycarbonylalkynyl group, an alkanoyl group, analkylaminocarbonoyl group, an alkynyl group, cyano group, analkoxycarbamoyl group, an alkylcarbamoyl group, di(alkanoyl)amino group,a halogen atom, an alkanoyloxy group, a phenylthio group, a phenoxythiogroup, a phenoxyoxythio group, a benzoylthio group, adi(alkoxy)phosphono group, a trimethylsilyl group, a di(alkoxy)borylgroup, a cycloalkyl group, a heterocyclic group which contains 1 to 4atoms selected from nitrogen atom, oxygen atom and sulfur atom as ahetero atom(s) (said heterocyclic group may have a substituent(s))or anaryl group which may have a substituent(s), etc. As a substituent forthe alkyl group of R, an alkoxycarbonyl group, cyano group or analkoxyalkyl group is preferably used. More specifically, those in whichR is 4-alkoxycarbonylbutyl group, 4-cyanobutyl group, 4-alkoxybutylgroup or 3-alkoxybutyl group are preferably used.

As the heterocyclic group which is a substituent for the alkyl group ofR, a saturated or unsaturated monocyclic or bicyclic heteroaromaticcyclic group may be mentioned, and there may be mentioned, for example,thienyl group, furyl group, tetrahydrofuryl group, pyranyl group,pyrrolyl group, imidazolyl group, pyrazolyl group, isothiazolyl group,isoxazolyl group, pyridyl group, pyrazinyl group, pyrimidinyl group,pyridazinyl group, pyrrolidinyl group, pyrrolinyl group, imidazolidinylgroup, imidazolinyl group, pyrazolidinyl group, pyrazolinyl group,piperidyl group, piperazinyl group, morpholinyl group, benzothienylgroup, benzofuryl group, isobenzofuranyl group, chromenyl group, indolylgroup, isoindolyl group, indazolyl group, purinyl group, quinolizinylgroup, naphthidinyl group, quinoxalinyl group, cinnolinyl group,quinolyl group, isoquinolyl group, benzothiazolyl group,benzisothiazolyl group, quinozolinyl group, phthalazinyl group,benzoxazolyl group, benzimidazolyl group, pteridinyl group,pyridopyrimidinyl group, isochromanyl group, chromanyl group, indolinylgroup, isoindolinyl group, tetrahydroquinolyl group,tetrahydroisoquinolyl group, tetrahydroquinoxalinyl group,dihydrophthalazinyl group, etc. As a substituent for the heterocyclicgroup, a dialkylamino group, an alkoxycarbonyl group, an alkyl group orformyl group may be mentioned.

Also, as the aryl group which is a substituent for the alkyl group of R,phenyl group, naphthyl group, anthracenyl group, etc. may be mentioned,and phenyl group is preferably used. As a substituent for the arylgroup, an alkoxycarbonyl group, an alkanoyl group, cyano group, analkanoyloxy group, an alkoxy group, di(trimethylsilyl)amino group, etc.may be mentioned.

As the bicyclo group of R, bicyclo[2.2.1]heptan-7-yl group,bicyclo[4.1.0]heptan-7-yl group, etc. may be mentioned. Also, as asubstituent for the bicycle group, an alkanoylamino group, etc. may bementioned.

As a substituent for the alkenyl group of R, a cycloalkyl group, an arylgroup which may have a substituent(s), an alkanoyloxy group, an alkanoylgroup, an alkylphenylsulfoxy group, a phenylsulfoxyamino group, ahalogenoalkyl group, etc. may be mentioned. As the aryl group, phenylgroup, naphthyl group, anthracenyl group, etc. may be mentioned, andphenyl group is preferably used. As a substituent for the aryl group, analkoxycarbonyl group, etc. may be mentioned.

As a substituent for the aryl group of R, an alkyl group, ahalogenoalkyl group, an alkoxycarbonyl group, an alkanoyl group, adialkylaminocarbonoyl group, cyano group, a halogen atom, etc. may bementioned. As the aryl group, phenyl group, naphthyl group, anthracenylgroup, etc. may be mentioned, and phenyl group is preferably used.

As the heterocyclic group which contains 1 to 4 atoms selected fromnitrogen atom, oxygen atom and sulfur atom as a hetero atom(s) of R, asaturated or unsaturated monocyclic or bicyclic heteroaromatic cyclicgroup may be mentioned, and there may be mentioned, for example, thienylgroup, furyl group, tetrahydrofuryl group, a pyranyl group, pyrrolylgroup, imidazolyl group, pyrazolyl group, isothiazolyl group, isoxazolylgroup, pyridyl group, pyrazinyl group, pyrimidinyl group, pyridazinylgroup, pyrrolidinyl group, pyrrolinyl group, imidazolidinyl group,imidazolinyl group, pyrazolidinyl group, pyrazolinyl group, piperidylgroup, piperazinyl group, morpholinyl group, benzothienyl group,benzofuryl group, isobenzofuranyl group, chromenyl group, indolyl group,isoindolyl group, indazolyl group, purinyl group, quinolizinyl group,naphthidinyl group, quinoxalinyl group, cinnolinyl group, quinolylgroup, isoquinolyl group, benzothiazolyl group, benzisothiazolyl group,quinozolinyl group, phthalazinyl group, benzoxazolyl group,benzimidazolyl group, pteridinyl group, pyridopyrimidinyl group,isochromanyl group, chromanyl group, indolinyl group, isoindolinylgroup, tetrahydroquinolyl group, tetrahydroisoquinolyl group,tetrahydroquinoxalinyl group, dihydrophthalazinyl group, etc., and ofthese, pyridyl group, thienyl group, imidazolyl group, thiazol group arepreferably used. As a substituent for the heterocyclic group, an alkylgroup, an alkoxycarbonyl group, benzoyl group, an alkanoyl group orcyano group, etc. may be mentioned.

Moreover, in the process of the present invention, it is preferred thatR is an alkyl group which may have a substituent(s), and as thesubstituent for the alkyl group, an alkoxycarbonyl group, cyano group oran alkoxy group is preferred. More specifically, R is preferably4-alkoxycarbonylbutyl group, 4-cyanobutyl group, 4-alkoxycarbonyl groupor 3-alkoxybutyl group. As the 4-alkoxycarbonylbutyl group,4-ethoxycarbonylbutyl group is mentioned.

In particular, in the process of the present invention, the reaction ispreferably carried out wherein R is an alkoxycarbonylalkyl group, acyanoalkyl group or an alkoxyalkyl group, by using zinc in the presenceof bromine.

Also, Compound (IX) can be produced by, after suspending zinc ormagnesium in a solvent and adding a salt (X), reacting with Compound(VIII). As the solvent, any solvent which does not cause any unfavorableeffect to the reaction may be used, and for example, tetrahydrofuran,toluene, diethyl ether, 1,2-dimethoxyethane, acetonitrile, 1,4-dioxane,etc. may be mentioned, and a mixed solvent of these solvents may beused. The present reaction proceeds at −50° C. to 150° C., particularlypreferably at 5° C. to 80° C. As a metal atom (M) of the salt (X), atypical metal or a transition metal, etc. may be mentioned. As thetypical metal, lithium, sodium, potassium, cesium, magnesium, calcium,barium, aluminum, zinc, silicon, tin, etc. may be mentioned, and as thetransition element, titanium, chromium, molybdenum, tungsten, manganese,iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper,etc. may be mentioned.

As a salt of the compounds represented by Compound (I), Compound (I-a),Compound (I-b), Compound (II), Compound (II′), Compound (II-a), Compound(II-b), Compound (II-c), Compound (III), Compound (III-a), Compound(IV), Compound (IV-a), Compound (VI), Compound (6) or Compound (6-a)which is obtained or obtainable in the present invention, there may bementioned, for example, inorganic salts (hydrochloride, phosphate,hydrobromide, sulfate, etc.) or a salt with an organic acid (acetate,formate, propionate, fumarate, maleate, succinate, tartarate, citrate,malate, oxalate, benzoate, methanesulfonate, benzenesulfonate, tosylate,etc.). Moreover, when the compound of the present invention has anacidic group such as a carboxylic acid, the compound of the presentinvention may form a salt with, for example, an inorganic base (analkali metal salt such as sodium salt, potassium salt, etc., an alkalineearth metal salt such as calcium salt, magnesium salt, etc., ammoniumsalt, etc.) or an organic base (an amino acid salt such as triethylaminesalt, lysine salt, etc.). A free compound and a salt can be mutuallyconverted into the other by a conventionally known method or a method inaccordance with the method.

In the present specification, as the alkyl group or the alkoxy group,straight or branched one having 1 to 6 carbon atoms, particularlystraight or branched one having 1 to 4 carbon atoms may be mentioned. Asthe alkanoyl group, the alkoxycarbonyl group or the alkylthiocarbonylgroup, straight or branched one having 2 to 7 carbon atoms, particularlystraight or branched one having 2 to 5 carbon atoms may be mentioned. Asthe halogen atom, fluorine atom, chlorine atom, bromine atom or iodineatom may be mentioned. As the halogenoalkyl group, trifluoromethylgroup, etc. may be mentioned.

EXAMPLE

Next, the present invention will be explained by referring to Examples,but the present invention is not limited only by such Examples.

Example 1

(1) In 45 ml of dimethylsulfoxide was dissolved 20 g of(4R)-3-benzyl-4-hydroxymethylthiazolidin-2-one under room temperature,1.45 ml of pyridine, 1.38 ml of trifluoroacetic acid, and 30 ml of ethylacetate were added to the solution in this order. At 25° C., 22.2 g ofdicyclohexylcarbodiimide and 15 ml of ethyl acetate were added to theabove mixture, and the resulting mixture was stirred at 50° C. for 3hours. To the reaction mixture was added 100 ml of ethyl acetate, themixture was stirred at 10° C. or lower for 30 minutes, and precipitatedproduct was filtered off. The filtrate was washed with brine (saturatedbrine:water=1:1), and the aqueous layer was further extracted with ethylacetate. The organic layers were combined, washed with brine (saturatedbrine:water=1:1), dried, and concentrated to obtain(4R)-2-oxo-3-benzylthiazolidin-4-carbaldehyde.

(2) The compound obtained in Example 1-(1) was dissolved in 50 ml ofdichloromethane, and at 20° C. to 25° C., 5 g of magnesium sulfate wasadded to the solution. At 5° C. or lower, 4.89 ml of benzylamine wasadded to the solution, and the resulting mixture was stirred at 20° C.to 25° C. for 1.5 hours. After cooling the solution to −5° C., 15 ml ofan aqueous solution containing 4.39 g of sodium cyanide and 5.1 ml ofacetic acid was added to the mixture at −5° C. to 0° C. Then, after atemperature of the solution was raised to 20° C. to 25° C. over 4 hours,it was stirred for 12 hours. To the solution was added 50 ml ofdichloromethane, and the mixture was washed with a saturated aqueoussodium hydrogen carbonate solution and water. The organic layer wasdried and concentrated to give 13.47 g of a mixture of a syn isomer andan anti isomer of(4R)-4-[1-(N-benzylamino)-1-cyanomethyl]-3-benzylthiazolidin-2-one aspale yellowish crystals. When optical purity of the mixture was analyzedby high performance liquid chromatography (HPLC), it had a ratio of synisomer:anti isomer=14:1.

(HPLC Conditions)

Column: L-column ODS (4.6×150 mm) [manufactured by ShimadzuCorporation], mobile layer: 0.01M KH₂PO₄ (pH=3)/acetonitrile=50/50, flowrate: 0.5 ml/min, UV detection: 225 nm, column temperature: 40° C.

syn isomer: Melting point: 124-125° C. [α]_(D) ²⁵: +46.1° (C=1.0,chloroform) Optical purity (HPLC): 99% ee

(HPLC Conditions)

Column: Chiral cell AD-H (4.6×250 mm) [manufactured by Daicel ChemicalIndustries, Ltd.], mobile layer: ethanol/n-hexane=10/90, flow rate: 0.8ml/min, UV detection: 225 nm, column temperature: 40° C.

anti isomer: MS.APCI (m/z): 338 [(M+H)⁺].

(3) The compound obtained in Example 1-(2) was suspended in 30 ml oftoluene, and under ice-cooling, 1.44 ml of water and 14.8 ml of conc.sulfuric acid were added to the suspension, and the mixture was stirredat 40° C. for 24 hours. At 30° C. or lower, 7 ml of water, 39 ml ofacetone, and 45 ml of water were added to the solution in this order.Then, at 40° C. or lower, 45 ml of conc. aqueous ammonia was added tothe solution, and the mixture was stirred at 25° C. for 30 minutes.Precipitated crystal was collected by filtration, washed with acetone,water, and acetone in this order, and dried to give 12.6 g of(4R)-4-[(1R)-1-(N-benzylamino)-1-carbamoylmethyl]-3-benzylthiazolidin-2-oneas pale yellowish crystal.

Melting point: 194-195° C. ESI.MS (m/z): 356 (M⁺+1) [α]_(D) ²⁰: −38.8°(C=0.45, N,N-dimethylformamide).

Example 2

In 200 ml of N,N-dimethylformamide was dissolved 100 g of(4R)-4-[(1R)-1-(N-benzylamino)-1-carbamoylmethyl]-3-benzylthiazolidin-2-one,and under nitrogen atmosphere, the solution was stirred at 85° C. for 5hours. At 90° C. to 95° C., 200 ml of 35% hydrochloric acid was addeddropwise to the solution, and the mixture was stirred for 1 hour and 15minutes. Moreover, 100 ml of 35% hydrochloric acid was added dropwise,and the mixture was stirred for 2 hours. Then, 200 ml of water was addeddropwise to the mixture at 85° C. The solution was ice-cooled, andprecipitated crystal was collected by filtration, washed with water andthen dried at 50° C. for 17 hours to give 93.1 g of(4R,5R)-1,3-dibenzyl-2-oxo-5-(mercaptomethyl)-imidazolidin-4-carboxylicacid as colorless crystal.

Melting point: 159-160° C. ESI.MS (m/z): 357 (M⁺+1) [α]_(D) ²⁰: +48.8°(C=0.62, N,N-dimethylformamide).

Example 3

To 240 ml of a chloroform solution containing 30 g of(4R,5R)-1,3-dibenzyl-2-oxo-5-(mercaptomethyl)imidazolidin-4-carboxylicacid, 22.7 g of pyridine and 2.6 ml of trifluoroacetic acid was addeddropwise 60 ml of a chloroform solution containing 17.4 g ofdicyclohexylcarbodiimide at 5° C. over 30 minutes. After the solutionwas refluxed for 5 hours, it was concentrated under reduced pressure.The concentrate was dissolved in ethyl acetate and concentrated, andafter the procedure was repeated, 300 ml of ethyl acetate was added tothe residue, and the mixture was stirred at 50° C. for 30 minutes. Aftercooling to 25° C., insoluble materials were filtered off. After thefiltrate was concentrated, 85 ml of methanol was added to theconcentrate and the mixture was dissolved under heating. After coolingthe solution, precipitated crystal was collected by filtration, andwashed with cold methanol. Precipitated crystal was dried by blowing airat 50° C. to give 21.3 g of(3aS,6aR)-1,3-dibenzyl-hexahydro-4H-thieno[3,4-d]imidazol-2,4-dione ascolorless crystal.

Melting point: 122-123° C. [α]_(D) ²⁵: +90.5° (C=1.0, chloroform).

Example 4

Under nitrogen atmosphere, 30.4 g of zinc powder was suspended in 55 mlof tetrahydrofuran, 3.5 ml of trimethylsilyl chloride was added to thesuspension, and the mixture was stirred for 15 minutes. After heating to40° C., dropwise addition of 102.9 g of ethyl 5-iodovalerate to themixture was started. Whereas exothermic reaction occurs simultaneouslywith starting the dropwise addition, the dropwise addition was continuedso that the mixture was maintained at 60° C. to 65° C. After completionof dropwise addition, the mixture was washed with 5 ml oftetrahydrofuran, immersed in an outer bath at 55° C. while continuingstirring (total time of the dropwise addition and stirring: 50 minutes),and after disappearance of ethyl 5-iodovalerate was confirmed by highperformance liquid chromatography, the mixture was cooled to 23° C. Tothe mixture were added 125 ml of toluene, 52.5 g of(3aS,6aR)-1,3-dibenzyl-hexahydro-4H-thieno[3,4-d]imidazol-2,4-dione,1.09 g of 10% palladium hydroxide on carbon, 50 ml of toluene, and 11.5ml of N,N-dimethylformamide in this order, and the resulting mixture wasstirred at 24° C. to 35.5° C. for 50 minutes. The reaction mixture wasfiltered by using 12 g of activated charcoal and 32.5 g of Celite, andwashed with 200 ml of tetrahydrofuran. The filtrate and the washingsolution were combined, and after washing with 2M hydrochloric acid, itwas washed with water and concentrated. The concentrated residue wasdissolved in 390 ml of toluene, 2.95 g of p-toluenesulfonicacid.monohydrate was added to the solution, and the mixture was stirredat 20° C. to 25° C. for 1.5 hours. At 40° C. to 45° C., about 100 ml ofthe solvent was distilled off, and the reminder was successively washedwith water, sodium thiosulfate aqueous solution and water in this order,and further concentrated to give 60.6 g of ethyl(5Z)-5-[(3aS,6aR)-1,3-dibenzyl-hexahydro-2-oxo-4H-thieno-[3,4-d]imidazol-4-yliden]pentanoateas oily product.

Example 5

400 ml of purified water, 12.85 g of 20% palladium hydroxide on carbon(50% wet), 900 ml of a methanol solution containing 249.5 g of ethyl(5Z)-5-[(3aS,6aR)-1,3-dibenzyl-hexahydro-2-oxo-4H-thieno[3,4-d]imidazol-4-yliden]pentanoatewere added successively in this order, and the atmosphere was replacedwith 490 kPa hydrogen three times. Moreover, 627 kPa hydrogen pressurewas applied at 6.5° C., and the mixture was stirred at 500 rpm. Thereaction temperature and the pressure became 92.5° C. and 843 kPa at 50minutes after initiation of heating, 117° C. and 921 kPa after 4 hours,and 116° C. and 853 kPa after 11 hours, so that hydrogen was charged upto 882 kPa. After 24 hours, the reaction mixture was cooled at 115° C.and 892 kPa, washed with methanol, and the catalyst was filtered off.The filtrate was concentrated, 400 ml of toluene was added to theresidue, and replacement and concentration were carried out three timeswith an outer bath at 65° C. To the above-mentioned residue were added1206 ml of methanol, 402 ml of water and 53.3 g of sodium hydroxide, theresulting mixture was stirred at 40° C. for 2 hours. To the reactionmixture was added 300 g of 10% aqueous hydrochloric acid, the mixturewas neutralized to pH 7, 6 g of activated charcoal was added to themixture and the resulting mixture was stirred at room temperature for 40minutes. The reaction mixture was subjected to precoat filtration with 6g of activated charcoal. Methanol was distilled of under reducedpressure, and 600 ml of ethyl acetate was added. 10% aqueoushydrochloric acid was added to the mixture to carry out extraction (pHof the aqueous layer was 0.7), and the organic layer was washed with 10%brine. The organic layer was dried over anhydrous magnesium sulfate, andfiltered. The filtrate was concentrated under reduced pressure, and whenno ethyl acetate was distilled off, the residue was subjected toreplacement with 170 ml of mesitylene and concentration two times togive 170.1 g of(3aS,4S,6aR)-1,3-dibenzyl-hexahydro-2-oxo-4H-thieno[3,4-d]imidazol-4-pentanoicacid as colorless oily product.

Example 6

A mixture of 3.0 g of(3aS,4S,6aR)-1,3-dibenzyl-hexahydro-2-oxo-4H-thieno[3,4-d]imidazol-4-pentanoicacid and 24 ml of 48% hydrobromic acid was refluxed at 110° C. to 120°C. for 48 hours. Hot extraction with 10 ml of toluene was carried outfour times to remove benzyl bromide. The aqueous layer was concentrated,15 ml of water and 11.5 ml of 6M aqueous sodium hydroxide solution wereadded to the residue, subsequently 3.36 g of ethoxycarbonyl chloride wasadded dropwise, and the reaction was carried out while maintaining pH to8 to 10, at room temperature for 3 hours. Thereafter, a temperature ofthe reaction mixture was raised to 70° C. to 80° C., and the reactionwas carried out for 20 hours (during the reaction, pH was maintained to12 by adding 6M aqueous sodium hydroxide solution). pH was adjusted to7.4 to 7.8 with 7 ml of 16% hydrochloric acid, and filtration wascarried out at 90° C. to 95° C. by using 1.0 g of activated charcoal.The filtrate was heated to 80° C. to 85° C., pH thereof was adjusted to1.8 to 2.2 by using 6 ml of 16% hydrochloric acid, and neutralizationcrystallization was carried out. After cooling, crystal was collected byfiltration and washed with water, and dried by blowing air at 50° C. togive 1.38 g of (+)-biotin as colorless crystal.

Example 7

(1) 79.3 g of (4R)-3-benzyl-4-hydroxymethylthiazolidin-2-one was treatedin the same manner as in Example 1-(2), and after the precipitatedcrystal was filtered off, the filtrate was concentrated. The residue waspurified by silica gel chromatography (hexane:chloroform:ethylacetate=5:5:1) to give 9.3 g of(4R)-4-[(1S)-1-(N-benzylamino)-1-cyanomethyl]-3-benzylthiazolidin-2-one.

Melting point: 131-132° C. [α]_(D) ²³: −174.7° (C=1.0, chloroform)MS.APCI (m/z): 338 [(M+H)⁺].

(2) 6.0 g of(4R)-4-[(1S)-1-(N-benzylamino)-1-cyanomethyl]-3-benzylthiazolidin-2-onewas treated in the same manner as in Example 1-(3) to give(4R)-4-[(1S)-1-(N-benzylamino)-1-carbamoylmethyl]-3-benzylthiazolidin-2-oneas colorless oily product. Then, it was dissolved in ethyl acetate, 6 mlof 4M hydrogen chloride-ethyl acetate solution was added, andprecipitated crystal was collected by filtration to give 4.3 g of(4R)-4-[(1S)-1-(N-benzylamino)-1-carbamoylmethyl]-3-benzylthiazolidin-2-onehydrochloride.

ESI.MS (m/z): 356 (M⁺+1) [α]_(D) ²³: −32.6° (C=1.0, methanol).

(3) In 10 ml of N,N-dimethylformamide was dissolved 0.541 g of(4R)-4-[(1S)-1-(N-benzylamino)-1-carbamoylmethyl]-3-benzylthiazolidin-2-onehydrochloride, the solution was stirred under nitrogen atmosphere at100° C. for 3 hours. Ethyl acetate was added to the reaction mixture,and the resulting mixture was washed with water, and saturated brine,dried and concentrated. The residue was crystallized from hexane to give342 mg of(3aS,6aR)-1,3-dibenzyl-hexahydro-4H-thieno[3,4-d]imidazol-2,4-dione ascolorless crystal.

Optical purity (HPLC): >91% ee

(HPLC Conditions)

Column: Chiral cell AD (4.6×250 mm) [manufactured by Daicel ChemicalIndustries, Ltd.], mobile layer: ethanol/hexane=15/85, flow rate: 0.8ml/min, UV detection: 225 nm, column temperature: 40° C.

Example 8

In 160 ml of chloroform was dissolved 20 g of(4R,5R)-1,3-dibenzyl-2-oxo-5-(mercaptomethyl)imidazolidin-4-carboxylicacid, 6.2 g of pyridine was added to the solution, and underice-cooling, 40 ml of a chloroform solution containing 12.7 g ofdicyclohexylcarbodiimide was added to the mixture at 15° C. or lower.The mixture was stirred at room temperature for 1 hour, ethyl acetatewas added to the reaction mixture and the resulting mixture wasfiltered. The filtrate was washed successively with 2M hydrochloricacid, water, a saturated sodium bicarbonate solution, and saturatedbrine. The organic layer was dried and then concentrated. The residuewas recrystallized from ethyl acetate to give 8.0 g of(3aR,6aR)-1,3-dibenzyl-hexahydro-4H-thieno[3,4-d]imidazol-2,4-dione.

Melting point: 115-116° C. [α]_(D) ²⁶: +10.6° (C=1.0, chloroform).

Example 9

In 1 ml of chloroform was dissolved 100 mg of(3aR,6aR)-1,3-dibenzyl-hexahydro-4H-thieno[3,4-d]imidazol-2,4-dione, 0.5ml of pyridine was added to the solution, and the resulting mixture wasstirred at room temperature for 23 hours. The reaction mixture wassuccessively washed with 2M hydrochloric acid, water, a saturated sodiumbicarbonate solution, and saturated brine. The organic layer was driedand then concentrated. By adding isopropyl ether, precipitated crystalwas collected by filtration to give 75.1 mg of(3aS,6aR)-1,3-dibenzyl-hexahydro-4H-thieno[3,4-d]imidazol-2,4-dione.

Melting point: 122-123° C. [α]_(D) ²⁵: +90.5° (C=1.0, chloroform).

Example 10

To 39 ml of an N,N-dimethylformamide solution containing 14 g of(4R)-4-[(1R)-1-(N-benzylamino)-1-carbamoylmethyl]-3-benzylthiazolidin-2-onewas added 3.96 g of sodium bicarbonate, and the mixture was stirred at80 to 85° C. for 17 hours. The reaction mixture was concentrated underreduced pressure, 40 ml of methanol and 20 ml of water were added to theconcentrated residue and the resulting mixture was stirred at 5° C. orlower for 1 hour. Precipitated crystal was collected by filtration,washed with a mixed solution comprising 80 ml of methanol and 40 ml ofwater, and then, dried by blowing air at 50° C. for 17 hours to give12.14 g of(4S,4′S,5R,5′R)-5,5′-[dithiobis(methylene)]bis(1,3-dibenzyl-2-oxoimidazolidin-4-carboxamide)as pale yellowish crystal.

Melting point: 208-211° C. ESI.MS (m/z): 709 (M⁺+1) [α]_(D) ²⁰: +55.4°(C=0.29, N,N-dimethylformamide).

Example 11

In 5 ml of acetic acid was dissolved 497 mg of(4S,4′S,5R,5′R)-5,5′-[dithiobis(methylene)]bis(1,3-dibenzyl-2-oxoimidazolidin-4-carboxamide),249 mg of zinc powder was added to the solution, and the resultingmixture was stirred at 90° C. for 1.5 hours. Ethyl acetate was added tothe reaction mixture and the mixture was filtered by adding Celite.After the filtrate was concentrated under reduced pressure, ether andhexane were added to the residue. Precipitated crystal was collected byfiltration, washed with water and hexane, and then, dried under reducedpressure to give 482 mg of(4R,5R)-1,3-dibenzyl-2-oxo-5-(mercaptomethyl)imidazolidin-4-carboxamideas colorless crystal.

Melting point: 119-122° C. ESI.MS (m/z): 356 (M⁺+1) [α]_(D) ²⁰: −1.2°(C=0.33, N,N-dimethylformamide).

Example 12

In 24 ml of acetic acid was dissolved 12 g of the compound obtained inExample 10, 7.2 g of zinc powder was added to the solution, and theresulting mixture was stirred at 55 to 60° C. for 1 hour. After thereaction mixture was cooled to 20° C., 72 ml of conc. hydrochloric acidwas added to the mixture and the resulting mixture was stirred at 80 to90° C. for 2 hours. To the reaction mixture was added 120 ml of water,and after cooling to 25° C. over 1 hour, the mixture was stirred at 5°C. or lower for 1 hour. Precipitated crystal was collected byfiltration, washed with 95 ml of water and dried under reduced pressureto give 11.05 g of(4R,5R)-1,3-dibenzyl-2-oxo-5-(mercaptomethyl)imidazolidin-4-carboxylicacid as colorless crystal.

Physical properties of this product accorded to those of Example 2.

Example 13

In 210 ml of dimethylsulfoxide was dissolved 23.5 g of(4R)-4-[(1R)-1-(N-benzylamino)-1-cyanomethyl]-3-benzylthiazolin-2-one,1.35 g of potassium carbonate (fine powder) was added to the solution,and further 12 ml of 30% aqueous hydrogen peroxide was added dropwise at20° C. to 25° C., and then, the resulting mixture was stirred at roomtemperature for 1 hour. To the liquid was further added 12 ml of 30%aqueous hydrogen peroxide, and after stirring at 20° C. for 13 hours,210 ml of water was added thereto at room temperature and the mixturewas stirred for 3 hours. Precipitated crystal was collected byfiltration, washed with water and acetone, and then, dried by blowingair at 50° C. overnight to give 21.8 g of(4R)-4-[(1R)-1-(N-benzylamino)-1-carbamoylmethyl]-3-benzylthiazolin-2-oneas colorless powder. Physical properties of this product accorded tothose of Example 1-(3).

Example 14

(1) In a mixed solution comprising 180 ml of tetrahydrofuran and 120 mlof toluene was suspended 92.8 g of zinc powder, 58 g of bromine wasadded at 10° C. to 37° C. over 15 minutes, and then, a temperature ofthe liquid was raised to 50° C. over 15 minutes. To the solution wasadded dropwise 186.4 g of ethyl 5-iodovalerate at 50° C. to 55° C. for3.5 hours.

(2) After cooling the solution obtained in Example 14-(1) to 30° C., 360ml of toluene, 176 g of(3aS,6aR)-1,3-dibenzyl-hexahydro-4H-thieno[3,4-d]imidazol-2,4-dione and44 ml of an N,N-dimethylformamide suspension containing 4.8 g ofpalladium catalyst (manufactured by Degussa Corporation; E 1002 NN/D 10%Pd) were successively added to the solution, and the resulting mixturewas stirred at 28° C. to 40° C. for 17 hours. To the solution was addedhydrochloric acid (157 ml of conc. hydrochloric acid+184 ml of water) at10° C. to 30° C., and the mixture was stirred at 20° C. for 1 hour.After filtration of the solution, a temperature of the filtrate wasraised to 40° C. over 40 minutes, and the solution was separated. Theorganic layer was washed successively with water, an aqueous sodiumhydrogen carbonate solution, an aqueous sodium sulfite solution, andwater in this order, and concentrated. Toluene was added to the residue,and the mixture was further concentrated. The residue was dissolved in67 ml of methanol, and 6.7 g of activated charcoal was added to thesolution and the mixture was filtered. The residue was washed with 67 mlof methanol, and combined with the filtrate to use the next step.

The product obtained by the above-mentioned reaction was partiallysaponified to make(5Z)-5-[(3aS,6aR)-1,3-dibenzyl-hexahydro-2-oxo-4H-thieno[3,4-d]imidazol-4-yliden]pentanoicacid and an amount thereof was quantitated by HPLC under the followingconditions whereby it had been confirmed that 220 g of ethyl(5Z)-5-[(3aS,6aR)-1,3-dibenzyl-hexahydro-2-oxo-4H-thieno[3,4-d]imidazol-4-yliden]pentanoatewas obtained by the above-mentioned reaction.

(HPLC Conditions)

Column: L-column ODS (4.6×150 mm) (manufactured by ShimadzuCorporation), mobile layer: acetonitrile/potassium hydrogen diphosphate(pH 3)=40/60, flow rate: 1.0 ml/min, UV detection: 254 nm, columntemperature: 40° C.

(3) To 88 ml of a methanol solution obtained in Example 14-(2) wereadded 313 ml of methanol, 110 ml of water and 9.06 g of palladiumcatalyst (manufactured by Degussa Corporation; E 106 NN/W 5% Pd), andthe mixture was stirred under a hydrogen pressure of 9 khPa at an innertemperature of 110° C. for 16 hours. After cooling the solution, thecatalyst was filtered off, and the filtrate was washed with 350 ml ofmethanol. To the filtrate was added an aqueous sodium hydroxide solution(14.6 g of sodium hydroxide+55 ml of water), and the mixture was stirredat 50° C. for 1 hour. To the solution was added 10% hydrochloric acid at30° C. or lower until the solution became pH 7, then the solution wasconcentrated. To the residue was added toluene, and the mixture wasfurther concentrated. After the residue was dissolved in 300 ml oftoluene, at 40° C. under heating, the mixture was washed with 10%hydrochloric acid and water. The organic layer was quantitated by HPLCunder the following conditions to confirm that 52 g of(3aS,4S,6aR)-1,3-dibenzyl-hexahydro-2-oxo-4H-thieno[3,4-d]imidazol-4-pentanoicacid obtained in the above-mentioned reaction was obtained.

(HPLC Conditions)

Column: L-column ODS (4.6×150 mm) (manufactured by Shimadzu), mobilelayer: acetonitrile/potassium hydrogen diphosphate (pH 3)=40/60, flowrate: 1.0 ml/min, UV detection: 254 nm, column temperature: 40° C.

(4) After the toluene solution obtained in Example 14-(3) wasconcentrated, mesitylene was added thereto and concentrated. The residuewas dissolved in 166 ml of mesitylene, 108 ml of methanesulfonic acidwas added to the solution, and the mixture was stirred at 133° C. for 1hour. The solution was cooled up to 80° C., 15 ml of acetic acid wasadded to the solution, and the solution was added dropwise to 1040 ml ofpurified water at 30° C. or lower. After the solution was ice-cooled for1 hour, precipitated crystal was collected by filtration, washed withwater and acetone, and dried under reduced pressure to give 25.7 g ofcrude biotin.

In an aqueous sodium hydroxide solution (4.42 g of sodium hydroxide+330ml of water) was dissolved 24.6 g of crude biotin, and a pH thereof wasadjusted to 8.5 at 50° C. to 60° C. by using dil. hydrochloric acid. Tothe solution was added 16 g of activated charcoal at 50° C. to 60° C.,and after the mixture was stirred for 10 minutes, and then, filtered.The filtrate was heated to 90° C. to 95° C., and a pH of the solutionwas adjusted to 1.8-2.2 with conc. hydrochloric acid, and then,neutralization crystallization were carried out. The mixture was stirredat the same temperature for 30 minutes to grow crystal. The solution wasgradually cooled, and after ice-cooling, precipitated crystal wascollected by filtration. The crystal was subjected to drying by blowingair at 50° C. overnight to give 22.4 g of (+)-biotin.

Reference Example 1

(1) A aqueous solution comprising 0.88 liter of water and 184.0 g ofsodium hydroxide was dissolved 175.6 g of L-cysteine monohydrochloridemonohydrate under ice-cooling, 0.35 liter of a toluene solutioncontaining 313.2 g of phenyl chloroformate was added to the abovesolution within a range not exceeding 30° C. After stirring the mixtureat room temperature for 2 hours, it was allowed to stand and the liquidswere separated. The aqueous layer was washed with 0.35 liter of toluene,the layers were separated, and the aqueous layer was concentrated togive 139.84 g of (4R)-2-oxothiazolidin-4-carboxylic acid as colorlesscrystal.

Melting point: 168-170° C. MS.APCI (m/z): 148 [(M+H)⁺] [α]_(D) ²⁵:−62.8° (C=1.0, H₂O).

(2) To 1.47 g of the compound obtained in Reference Example 1-(1) weresuccessively added an aqueous solution comprising 1.5 ml of water and anaqueous solution containing 0.6 g of sodium hydroxide and 4.4 ml ofdimethylsulfoxide under ice-cooling. To the mixture was added 2.3 ml ofbenzyl chloride at room temperature, and the resulting mixture wasstirred for 15 hours. The mixture was neutralized by dil. hydrochloricacid, and extracted with ethyl acetate. The organic layer was washedwith water and saturated brine, dried over anhydrous magnesium sulfate,and then, insoluble material was filtered off and the filtrate wasconcentrated to give 2.24 g of(4R)-2-oxo-3-benzylthiazolidin-4-carboxylic acid as colorless crystal.

Melting point: 95-97° C. MS.APCI (m/z): 238 [(M+H)⁺] [α]_(D) ²⁵: −102.2°(C=1.0, chloroform).

(3) To 32 ml of tetrahydrofuran was added 1.53 g of sodium borohydrideunder room temperature, and the mixture was cooled to 10° C. To themixture was added 8.0 g of the compound obtained in Reference Example1-(2), and further 2 ml of a tetrahydrofuran solution containing 2.0 gof sulfuric acid was added to the mixture. The mixture was stirred at40° C. to 50° C. for 3 hours, the reaction mixture was ice-cooled and 2Mhydrochloric acid was added to the mixture until a pH of the mixturebecame 1. The reaction mixture was diluted with ethyl acetate, and thelayers were separated. The organic layer was washed with water, driedover anhydrous magnesium sulfate, and then concentrated under reducedpressure. The residue was recrystallized from diisopropyl ether to give6.82 g of (4R)-3-benzyl-4-hydroxymethylthiazolidin-2-one as colorlesscrystal.

Melting point: 87-90° C. MS.APCI (m/z): 224 [(M+H)⁺] [α]_(D) ²⁵: −26.7°(C=1.0, methanol) Optical purity (HPLC): >99% ee

(HPLC Conditions)

Column: Chiral cell AD (4.6×250 mm) [manufactured by Daicel ChemicalIndustries, Ltd.], mobile layer: ethanol/hexane=10/90, flow rate: 0.8ml/min, UV detection: 225 nm, column temperature: 40° C.

(4) In 5.0 ml of dimethylsulfoxide was dissolved 1.0 g of the compoundobtained in Reference Example 1-(3), and 1.95 ml ofdiisopropylethylamine was added dropwise thereto under room temperature.The reaction mixture was ice-cooled, and then, 1.78 g of sulfur trioxidepyridine complex salt was added thereto at 12° C. to 20° C., and theresulting mixture was stirred at the same temperature for 30 minutes.The reaction mixture was poured into 30 ml of ice-cold water, andextracted with 20 ml of ethyl acetate. The aqueous layer was extractedagain with 10 ml of ethyl acetate. The ethyl acetate layers werecombined, washed twice with 10 ml of 10% citric acid, and then, washedwith 10 ml of water and 10 ml of saturated brine, respectively. Theextract was dried over anhydrous magnesium sulfate, and concentratedunder reduced pressure to give 985.9 mg of(4R)-2-oxo-3-benzylthiazolidin-4-carbaldehyde as colorless oily product.

MS.APCI (m/z): 222 [(M+H)⁺].

Reference Example 2

In 22 ml of dichloromethane was dissolved 2.34 g of dimethylsulfoxide,and 1.31 ml of oxalyl chloride was added thereto at −78° C. Afterstirring the mixture at the same temperature for 10 minutes, 11 ml of adichloromethane solution containing 2.23 g of the compound obtained inReference Example 1-(3) was added dropwise to the mixture at −60° C. orlower. After stirring the mixture at −78° C. for 20 minutes, 5.58 ml oftriethylamine was added dropwise at −60° C. or lower. A reactiontemperature of the mixture was raised to −20° C. over 1.5 hours, andthen, the reaction mixture was added to 10% aqueous citric acid, and thelayers were separated. The organic layer was washed with saturatedbrine, dried over anhydrous magnesium sulfate, and concentrated underreduced pressure to give 2.20 g of the same objective compound as inReference Example 1-(4). Physical properties of this product accorded tothose of Reference Example 1-(4).

Reference Example 3

In 11 ml of dichloromethane was dissolved 532 mg of chlorine, and 0.73ml of dimethylsulfide was added thereto at −20° C. to −10° C. Afterstirring the mixture at the same temperature for 10 minutes, 5.5 ml of adichloromethane solution containing 1.12 g of the compound obtained inReference Example 1-(3) was added dropwise thereto at −25° C. Afterstirring the mixture at −25° C. for 20 minutes, 2.79 ml of triethylaminewas added dropwise thereto at −25 to −18° C. After stirring the mixtureat −25° C. for 10 minutes, the reaction mixture was added to 10% aqueouscitric acid, and the layers were separated. The organic layer was washedwith saturated brine, dried over anhydrous magnesium sulfate, andconcentrated under reduced pressure to give 1.17 g of the same objectivecompound as in Reference Example 1-(4). Physical properties of thisproduct accorded to those of Reference Example 1-(4).

Reference Example 4

In a mixed solvent comprising 6 ml of dichloromethane and 1 ml of waterwere dissolved 447 mg of the compound obtained in Reference Example1-(3), 6.9 mg of 4-hydroxytetramethylpiperidineoxide and 206 mg ofsodium bromide, and a mixture comprising 1.49 g of aqueous sodiumhypochlorite, 491 mg of sodium bicarbonate and 5 ml of water wasgradually added dropwise to the solution while effecting nitrogenbubbling and under ice-cooling. After stirring the mixture for one hour,the layers were separated, and the organic layer was washed with 16 mgof potassium iodide, a 10% aqueous potassium hydrogen sulfate solutionand an aqueous sodium thiosulfate solution, respectively. The organiclayer was dried over anhydrous magnesium sulfate, and concentrated underreduced pressure to give 147.5 mg of the same objective compound as inReference Example 1-(4). Physical properties of this product accorded tothose of Reference Example 1-(4).

Reference Example 5

(1) To the solution comprising 2 liters of water containing 180 g ofsodium hydroxide was dissolved 175.6 g of L-cysteine monohydrochloridemonohydrate under ice-cooling and under nitrogen atmosphere. To thesolution was added dropwise 700 ml of a 1,4-dioxane solution containing118.7 g of triphosgene at 25° C. to 29° C. over 1 hour and 30 minutes,and further stirred at the same temperature for 3 hours. To the reactionmixture was added conc. hydrochloric acid to adjust the mixture to weakacidic solution, and then, the solvent was removed under reducedpressure. To the concentrated residue was added 200 ml of toluene, andthe solvent was removed again under reduced pressure. To theconcentrated residue was added 700 ml of ethanol, 131 g of thionylchloride was added to the mixture under ice-cooling over 40 minutes, andthe resulting mixture was stirred for 19 hours while raising thetemperature to room temperature. The solvent was removed under reducedpressure, and then, the concentrated residue was dissolved in 1 liter ofethyl acetate, and the mixture was successively washed with 700 ml ofwater, 300 ml of an aqueous saturated sodium bicarbonate solution and500 ml of saturated brine. After the mixture was dried over anhydrousmagnesium sulfate, and the solvent was removed under reduced pressure togive 162 g of ethyl (4R)-2-oxothiazolidin-4-carboxylate as oily product.

MS.APCI (m/z): 176 [(M+H)⁺] [α]_(D) ²⁵: −52.7° (C=1.0, chloroform).

(2) 1.79 g of sodium bromide, 5 ml of N,N-dimethylacetamide and 1 ml ofbenzyl chloride were stirred at 23° C. to 26° C. for 15 hours to givebenzyl bromide. Into the solution were added 1.27 g of the compoundobtained in Reference Example 5-(1), 2 ml of N,N-dimethylacetamide and1.1 g of potassium carbonate, and the mixture was reacted at 23° C. to30° C. for 93 hours. Then, ethyl acetate and 10% aqueous citric acidwere added to the mixture, and the aqueous layer was separated. Theorganic layer was washed with water, dried over anhydrous magnesiumsulfate, and then concentrated to give 2.29 g of the residue. Theresidue was purified by silica gel column chromatography (solvent:n-hexane:ethyl acetate=5:1) to give 1.67 g of ethyl(4R)-2-oxo-3-benzylthiazolidin-4-carboxylate as colorless oily product.

MS.APCI (m/z): 266 [(M+H)⁺] [α]_(D) ²⁴: −96.6° (C=1.0, chloroform)Optical purity (HPLC): 98.1% ee

(HPLC Conditions)

Column: Chiral cell OD (4.6×250 mm) [manufactured by Daicel ChemicalIndustries, Ltd.], mobile layer: ethanol/hexane=5/95, flow rate: 0.8ml/min, UV detection: 225 nm, column temperature: 40° C.

Reference Example 6

In 227 ml of ethanol was dissolved 28.4 g of ethyl(4R)-2-oxo-3-benzylthiazolidin-4-carboxylate, 2.26 g of sodiumborohydride was added to the solution, and the resulting mixture wasstirred at room temperature for 15 hours. Moreover, 0.76 g of sodiumborohydride was additionally added to the mixture, and the resultingmixture was stirred at room temperature for 2 hours. To the mixture wasadded conc. hydrochloric acid to neutralize the mixture to be a pH of 6to 7, and the solution was concentrated. The concentrated residue wasdissolved in ethyl acetate, washed three times with water, and theaqueous layer was reverse extracted once with ethyl acetate. The ethylacetate layers were combined, dried over anhydrous magnesium sulfate,and then, concentrated to give 22.6 g of an oily residue. Isopropylether was added to the residue to crystallize the compound, and furtherthe crystal was collected by filtration, washed with isopropyl ether,and dried under reduced pressure to give 18.4 g of(4R)-3-benzyl-4-hydroxymethylthiazolidin-2-one as colorless crystal.Physical properties of this product accorded to those of ReferenceExample 1-(3).

Reference Example 7

(1) In 200 ml of acetonitrile was dissolved 10 g of(4R)-2-oxo-3-benzylthiazolidin-4-carboxylic acid, and 9.2 g ofdicyclohexylcarbodiimide was added to the solution under roomtemperature. Subsequently, to the solution were added 3.3 ml ofethanethiol, and 670 mg of 4-dimethylaminopyridine in this order underice-cooling, and the mixture was stirred at room temperature for 2hours. Insoluble material was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was purified by silicagel column chromatography (solvent: n-hexane:ethyl acetate=10:1) to give10.8 g of (4S)-4-ethylthiocarbonyl-3-benzylthiazolidin-2-one as oilyproduct.

MS.APCI (m/z): 282 [(M+H)⁺] [α]_(D) ²⁵: −110.8° (C=1.04, chloroform).

(2) In 5.0 ml of dichloromethane was dissolved 0.5 g of the compoundobtained in Reference Example 7-(1), and 284 mg of palladium hydroxidewas added to the solution under nitrogen atmosphere. At roomtemperature, 0.85 ml of trimethylsilane was added to the mixture, andthe resulting mixture was stirred at the same temperature for 3 hours.Insoluble material was filtered off, and the filtrate was concentratedunder reduced pressure to give 0.5 g of(4R)-2-oxo-3-benzylthiazolidin-4-carbaldehyde as oily product. Physicalproperties of this product accorded to those of Reference Example 1-(4).

Reference Example 8

35.34 g of the compound obtained in Example 5, 121 ml of mesitylene and116.1 g of methanesulfonic acid were heated at an inner temperature of130° C. By setting a reaction starting time when the mixture reached to125° C., the mixture was stirred at 128° C. to 133° C. for 4 hours,disappearance of monobenzylbiotin was confirmed by high performanceliquid chromatography. The reaction mixture was cooled to 80° C., 30 mlof acetic acid was added thereto, and methanesulfonic acid layer wasadded dropwise to 710 ml of purified water. The mesitylene layer wasseparated, ice-cooled for 1 hour, and then, crude crystal was collectedby filtration, and washed with 200 ml of water, and then, with methanoluntil black color of the washed solution disappeared. The crystal wasdried at 50° C. by blowing air overnight to give 15.89 g of crude(+)-biotin.

The obtained crude (+)-biotin was dissolved in an aqueous solutioncomprising 160 ml of purified water containing 2.73 g of sodiumhydroxide, and a pH of the solution was adjusted to 7 by using dil.hydrochloric acid at 90° C. to 95° C. At 90° C. to 95° C., 4 g of carbonpowder was added into the system, and after stirring the mixture for 10minutes, carbon powder precoate filtration was carried out. The filtratewas heated to 90° C. to 95° C. again, and 4 g of powder was again addedto the system, and after the mixture was stirred for 10 minutes, thecarbon coate precoat was filtered off. The filtrate was heated to 80° C.to 85° C. again, and a pH of the mixture was adjusted to 1.8 to 2.2 withconc. hydrochloric acid, and neutralization crystallization were carriedout. The mixture was stirred at the same temperature for 1 hour to growcrystal. The mixture was gradually cooled, ice-cooled and then thecrystal was collected by filtration. The crystal was dried by blowingair at 50° C. overnight to give 13.86 g of (+)-biotin as colorlesscrystal.

INDUSTRIAL APPLICABILITY

The process for preparing biotin of the present invention which usesCompound (IV) as a synthetic intermediate or the process for preparingbiotin which uses Compound (I) and Compound (III) prepared by theprocesses of the present invention as a synthetic intermediate canproduce biotin inexpensively as compared to the conventionally knownprocesses mentioned in literatures, so that they become industriallyadvantageous processes of biotin.

1. A process for preparing a compound represented by the formula (I):

wherein R¹ and R² are the same or different from each other, and eachrepresents a hydrogen atom, a benzyl group optionally having asubstituent(s) on the benzene ring, a benzhydryl group optionally havinga substituent(s) on the benzene ring, or a trityl group; R³ represents acyano group, a carboxyl group, an alkoxycarbonyl group, analkylthiocarbonyl group, or a carbamoyl group optionally having asubstituent, or a salt thereof;  said method comprising: subjecting acompound represented by the formula (II-a) or a salt thereof to ringtransformation by reacting the compound at 0° C. to 200° C.:

 wherein the symbols have the same meanings as defined above; therebyproducing the compound of formula (I).
 2. The process according claim 1,wherein the ring transformation proceeds at 80° C. to 100° C.
 3. Theprocess according to any one of claims 1 and 2, wherein R¹ and R² arethe same or different, and each represents (1) hydrogen atom, (2) abenzyl group in which the benzene ring is optionally substituted by agroup(s) selected from the group consisting of a halogen atom, an alkylgroup and an alkoxy group, (3) a benzhydryl group in which the benzenering is optionally substituted by a group(s) selected from the groupconsisting of a halogen atom, an alkyl group and an alkoxy group, or (4)a trityl group in which the benzene ring is optionally substituted by agroup(s) selected from the group consisting of a halogen atom, an alkylgroup and an alkoxy group, and R³ is (1) cyano group, (2) carboxylgroup, (3) an alkoxycarbonyl group, (4) an alkylthiocarbonyl group, or(5) a carbamoyl group optionally substituted by an alkyl group.
 4. Theprocess according to any one of claims 1 and 2, wherein R¹ and R² bothrepresent benzyl groups, benzhydryl groups or trityl groups, and R³represents a carboxyl group, an alkoxycarbonyl group or a carbamoylgroup.